bild

Wildlife corridor across a road. Bridges (or sometimes tunnels) are constructed to enable terrestrial animals to cross man-made barriers, such as roads. These corridors are important for maintaining the movement and migration of animals in habitats that have been fragmented by the actions of humans, and for preventing road casualties. Photographed in Banff National Park, Canada. (KEYSTONE/SCIENCE PHOTO LIBRARY/ALAN SIRULNIKOFF)